If you want to add rocks to your aquarium, there are basically two ways to go about it. First one would be to simply buy one from an aquarium store. The other choice would be to find some rocks on your own. Understandably, a store-bought rock is ready-to-use. However, since store-bought rocks are somewhat processed and prepared for, they can cost quite a bit.

If you choose to pick your own aquarium rocks, you need to follow some rules. You just can’t add any type of rock to your aquarium. You have to consider many things if you wish to ensure the safety and balance of your fish tank. If somehow, you managed to get the wrong rock in your fish tank, the result could be catastrophic.

How should I choose my aquarium rocks?

Obviously, you would save money by getting your own rocks. However, if you choose the wrong kind of rock, you may be risking the health of your aquarium. If you just pick out a random rock in your backyard, there is a high chance that they alter the water parameters of your aquarium. Some rocks can change the pH and hardness level of the water. If you try to maintain a constant pH on your water, you will find that some rocks can change it dramatically.

Another thing that you need to watch out for is the growth for bacteria. Some rocks may harbor a host of bacteria which can easily thrive inside an aquarium. A good rule is not to take rocks from dirty and polluted areas. You also want to get a solid rock and not a brittle one since it can easily crumble inside the aquarium due to water erosion.

You may be thinking to just get an aquarium near river banks since these rocks are used to water. Problem solved, right? Well actually, that isn’t recommended either. Rocks from streams and ponds will carry potentially harmful bacteria and other microscopic organisms to which, although helpless outside, will be harmful inside the aquarium. Although it makes a lot of sense, using rocks found near bodies water would almost always end badly.

Make sure that the rocks you’re going to introduce to your aquarium don’t contain any metal. Many metals will rust under water which is no good for the health of the fish. Avoid any metallic rocks on your aquarium at all costs.

In summary, here’s what you need to avoid when getting rocks for your aquarium:

  • Don’t just get any random rock
  • No rocks from river or bodies of water
  • No rocks from polluted areas
  • No metallic rocks

Testing Found Rocks Outside

Looking to test rocks that you found outside to see if they are aquarium safe? Well check out the video below to see how most hobbyists determine if a rock is eligible to be used in an aquarium.

What types of rocks to get?

Though it may seem that there are a lot of restrictions when selecting a rock for your home aquarium, there is quite a huge selection of rocks that is safe for your aquarium. These rocks can easily be found in most areas and are can easily be identified.

Here are some rocks that are safe and neutral:

  • Granite
  • Lava rock
  • Petrified Wood
  • Quartz
  • Slate

Make sure to only use rocks that fall into these types. Although some of the rocks in the list have a tendency to increase pH and water hardness, it doesn’t actually matter that much. The increase is normal and oftentimes negligible and depends on where you get the rock from.

The type of rock you need to avoid is carbonate rock. It can increase water hardness and pH and affect the overall health of the fish tank. Some tanks can tolerate this increase but soft water tanks would be impacted negatively. Make sure to check your water chemistry regularly if you want to ensure optimal water hardness and pH.

Since some of carbonate rock can be mistaken for other rocks, you should know how to test them. An easy way to test is to apply a few drops of white vinegar on the rock’s surface. If the droplet fizzes when in contact with the surface, most likely the rock has carbonate content. Using this type of rock for your aquarium can make the pH and hardness unpredictable. You can substitute hydrochloric acid to white vinegar if you want to increase the accuracy of this test.

Here are the most commonly found carbonate rocks:

  • Alabaster
  • Coral
  • Crushed Seashells
  • Dolomite
  • Limestone
  • Many types of sandstone
  • Marble

Preparing the rocks to be placed inside the aquarium

Once you’ve chosen the rocks that are safe for your aquarium, the next thing to do is to prepare them. The obvious thing to do is to clean them. The rocks should be scrubbed with a stiff brush in running water. Only use water and brush when cleaning the rocks. You don’t want to leave any residue on the rock after cleaning it. Even a simple chemical residue can impact the balance of your fish tank.

Once you are confident in the cleanliness of the rock, further cleaning is still needed. To ensure that absolutely no chemical residue or bacteria is left on the rock, you need to boil. Boiling the rocks would kill any bacteria that may still be living inside and outside of the rock. Another choice would be to bleach the rock.

Boiling the rocks

Find a cooking pot that is both large and deep enough to allow several rocks be submerged under water. Do not add any additives in the water. Tap water will do. Set the stove on medium-high fire and wait for the water to boil. This usually takes around 10 minutes.

After boiling the rocks for about 20-30 minutes, removed them from the pot. Place the rocks on some paper towels to allow them to dry. Leave them in an open area to cool them down; this should take about an hour. Once the rock is cool to the touch, you can now safely add them to your aquarium.

When boiling rocks, safety precautions need to be exercised. If the rocks are left unattended and boiling for too long, they can explode. Although this rarely happens, it is still a good idea to practice safety when dealing with heat and kitchen equipment. You don’t want to damage your kitchen over boiling rocks, do you?

Another word of advice, remember that boiling won’t work for porous rocks. Attempting to boil this type of rock will result in them crumbling and breaking apart as soon as the water starts to boil. For porous rocks, bleaching is usually the usual choice.

Using bleach for cleaning the rocks

Submerging the rocks in a bleach solution is another way to remove any impurities or bacteria from the rocks. It may not be as effective as boiling the rocks but it is still effective in removing unwanted materials from them. It is best to use this method for porous rocks to keep them from breaking apart.

What you need to do is find a container large enough to contain your rocks. Make sure that the container is deep enough as to allow the rocks to be fully submerged in the solution. The solution should have a ratio of 10:1 water to bleach. Allow the rocks to sit there for 24 hours. After that, carefully remove them from the solution and rinse them with running water. To fully remove any trace of the bleach solution, you can have the rocks submerged once again for a couple of hours.

Placing the rocks to your aquarium safely

One of the most common mistakes people make when putting rocks inside their tank is piling them up against the glass. When put under enough pressure and weight, glass will crack. Most aquarium glass panes are quite strong but under additional stress from the weight of the rocks, they could easily break. What you need to do is to place the rocks wisely inside the tank. Avoid cramming the rocks in one area of the aquarium. A better placement would be to have them uniformly placed inside the aquarium. However, if cramming of rocks is unavoidable (due to the design you are going for), just make sure that the glass pane can handle the additional weight of the rocks.

You also need to secure the rocks in place. If you do not secure your rocks inside the aquarium, a rock can be knocked down by a rogue fish causing it to fall into the aquarium glass ultimately cracking it down. Obviously, you don’t want that risk. To prevent that from happening, use aquarium silicone glue. Always make sure that you use non-toxic glue though. Most fish stores will have them on their stock.

If you follow all these tips, you would safely create a safe and attractive environment for your fish.

Looking for Aquarium Safe Rocks for Sale?

Aquatic Mag is now selling all sorts of aquarium rocks directly to your doorstep. Check out below for which rocks we have in stock.